chore: Bump version to 0.1.6post2 and update CHANGES accordingly
fix: Incorrect build tag
fix: Content-Length header always 0 for resp.data

Currently, the Content-Length header is always set to zero when
resp.data was used in lieu of resp.body. This patch fixes
the content_length helper so that it now checks for resp.data,
in addition to resp.body and resp.stream.